The present invention relates generally to devices and methods for performing surgery on the heart. More specifically, the invention relates to less-invasive devices and methods for the surgical treatment of diseased heart valves.
Heart valve disease is a widespread condition in which one or more of the valves of the heart fails to function properly. Diseased heart valves may be categorized as either stenotic, wherein the valve does not open sufficiently to allow adequate forward flow of blood through the valve, or incompetent, wherein the valve does not close completely, causing excessive backward flow of blood through the valve when the valve is closed. A heart valve may also be both stenotic and incompetent. Valve disease can be severely debilitating and even fatal if left untreated, particularly if the diseased valve is the mitral valve (between the left atrium and left ventricle) or the aortic valve (between the left ventricle and the aorta). According to recent estimates, more than 80,000 patients are diagnosed with aortic or mitral valve disease in U.S. hospitals each year.
Various surgical techniques may be used to repair a diseased or damaged valve. One repair technique which has been shown to be effective in treating incompetence, particularly of the mitral and tricuspid valves, is annuloplasty, in which the effective size of the valve annulus is contracted by attaching a prosthetic annuloplasty ring to an interior wall of the heart around the valve annulus. The annuloplasty ring comprises an inner substrate of a metal such as stainless or titanium, or a flexible material such as silicone rubber or Dacron cordage, covered with a biocompatible fabric or cloth to allow the ring to be sutured to the heart tissue. The annuloplasty ring may be stiff or flexible, may be split or continuous, and may have a variety of shapes, including circular, D-shaped, C-shaped, or kidney-shaped. Examples are seen in U.S. Pat. Nos. 4,917,698, 5,061,277, 5,290,300, 5,350,420, 5,104,407, 5,064,431, 5,201,880, and 5,041,130, which are incorporated herein by reference.
Annuloplasty rings may also be utilized in combination with other repair techniques such as quadrangular resection, in which a portion of a valve leaflet is excised, the remaining portions of the leaflet are sewn back together, and a prosthetic annuloplasty ring is then attached to the valve annulus to maintain the contracted size of the valve. Other valve repair techniques in current use include commissurotomy (cutting the valve commissures to separate the valve leaflets), shortening mitral or tricuspid valve chordae tendonae, reattachment of severed mitral or tricuspid valve chordae tendonae or papillary muscle tissue, and decalcification of the valve leaflets or annulus. Annuloplasty rings may be used in conjunction with any repair procedures where contracting or stabilizing the valve annulus might be desirable.
In cases where a cardiac valve is not suited to repair, the valve may be replaced, by excising the valve leaflets of the natural valve, and securing a replacement valve in the valve position, usually by suturing the replacement valve to the natural valve annulus. Various types of replacement valves are in current use, including mechanical and biological prostheses, homografts, and allografts, as described in Bodnar and Frater, Replacement Cardiac Valves 1-357 (1991). A comprehensive discussion of heart valve diseases and the surgical treatment thereof is found in Kirklin and Barratt-Boyes. Cardiac Surgery 323-459 (1986).
Using current techniques, most valve repair and replacement procedures require a gross thoracotomy, usually in the form of a median sternotomy, to gain access into the patient""s thoracic cavity. A saw or other cutting instrument is used to cut the sternum longitudinally, allowing two opposing halves of the anterior or ventral portion of the rib cage to be spread apart. A large opening into the thoracic cavity is thus created, through which the surgical team may directly visualize and operate upon the heart and other thoracic contents. Alternatively, a thoracotomy may be performed on a lateral side of the chest, wherein a large incision is made generally parallel to the ribs, and the ribs are spread apart and/or removed in the region of the incision to create a large enough opening to facilitate the surgery.
Surgical intervention within the heart generally requires isolation of the heart and coronary blood vessels from the remainder of the arterial system, and arrest of cardiac function. Usually, the heart is isolated from the arterial system by introducing an external aortic cross-clamp through a sternotomy and applying it to the aorta to occlude the aortic lumen between the brachiocephalic artery and the coronary ostia. Cardioplegic fluid is then injected into the coronary arteries, either directly into the coronary ostia or through a puncture in the ascending aorta, so as to arrest cardiac function. In some cases, cardioplegic fluid is injected into the coronary sinus for retrograde perfusion of the myocardium. The patient is placed on extracorporeal cardiopulmonary bypass to maintain peripheral circulation of oxygenated blood.
Of particular interest in the present application are techniques for the repair and replacement of the mitral valve. The mitral valve, located between the left atrium and left ventricle of the heart, is most easily reached through the wall of the left atrium, which normally resides on the posterior side of the heart, opposite the side of the heart that is exposed by a median sternotomy. Therefore, to access the mitral valve via a sternotomy, the heart is rotated to bring the left atrium into an anterior position accessible through the sternotomy. An opening, or atriotomy, is then made in the right side of the left atrium, anterior to the right pulmonary veins. The atriotomy is retracted by means of sutures or a retraction device, exposing the mitral valve directly posterior to the atriotomy. One of the forementioned techniques may then be used to repair or replace the valve.
An alternative technique for mitral valve access may be used when a median sternotomy and/or rotational manipulation of the heart are inappropriate. In this technique, a thoracotomy is made in the right lateral side of the chest, usually in the region of the fourth or fifth intercostal space. One or more ribs may be removed from the patient, and other ribs near the incision are retracted outward to create a large opening into the thoracic cavity. The left atrium is then exposed on the posterior side of the heart, and an atriotomy is formed in the wall of the left atrium, through which the mitral valve may be accessed for repair or replacement.
Using such open-chest techniques, the large opening provided by a median sternotomy or right thoracotomy enables the surgeon to see the mitral valve directly through the left atriotomy, and to position his or her hands within the thoracic cavity in close proximity to the exterior of the heart for cannulation of the aorta and/or coronary arteries to induce cardioplegia, manipulation of surgical instruments, removal of excised tissue, and introduction of an annuloplasty ring or a replacement valve through the atriotomy for attachment within the heart. However, these invasive, open-chest procedures produce a high degree of trauma, a significant risk of complications, an extended hospital stay, and a painful recovery period for the patient. Moreover, while heart valve surgery produces beneficial results for many patients, numerous others who might benefit from such surgery are unable or unwilling to undergo the trauma and risks of current techniques.
What is needed, therefore, are devices and methods for carrying out heart valve repair and replacement as well as other procedures within the heart and great vessels that reduce the trauma, risks, recovery time and pain that accompany current techniques. The devices and methods should facilitate surgical intervention within the heart or great vessels without the need for a gross thoracotomy, preferably through small incisions within intercostal spaces of the rib cage, without cutting, removing, or significantly deflecting the patient""s ribs or sternum. In particular, the devices and methods should allow for removal of tissue from the thoracic cavity, as well as for introduction of surgical instruments, visualization devices, annuloplasty rings, replacement valves, and the like into the thoracic cavity, to facilitate heart valve repair and replacement. The devices and methods should enable the implantation of annuloplasty rings of various shape, size, and stiffness. In addition, the devices and methods should facilitate replacement of a heart valve with various types of prostheses, including mechanical and biological prostheses, homografts, and allografts.
The invention provides devices and methods for performing less-invasive surgical procedures within an organ or vessel, and particularly, within the heart and great vessels of the thoracic cavity. The devices and methods of the invention facilitate intervention within the heart and great vessels without the need for a median sternotomy or other form of gross thoracotomy, substantially reducing trauma, risk of complication, recovery time, and pain for the patient. Using the devices and methods of the invention, surgical procedures may be performed through percutaneous penetrations within intercostal spaces of the patient""s rib cage, without cutting, removing, or significantly displacing any of the patient""s ribs or sternum. The devices and methods are particularly well-adapted for heart valve repair and replacement, facilitating visualization within the patient""s thoracic cavity, repair or removal of the patient""s natural valve, and, if necessary, attachment of an annuloplasty ring or a replacement valve in the natural valve position. The invention facilitates valve repair with a variety of different annuloplasty rings, as well as valve replacement with any of a variety of replacement valves, including mechanical prostheses, bioprostheses, homografts, and allografts.
According to the invention, access into the chest cavity and into the heart is obtained by means of small incisions, punctures, cannulae, trocars, or other percutaneous penetrations of minimal size positioned in the intercostal spaces between adjacent ribs of the rib cage. In this application, these percutaneous penetrations within intercostal spaces will be referred to as xe2x80x9cintercostal ports.xe2x80x9d The intercostal ports utilized in the present invention will not require removal, cutting, or other modification of the ribs or sternum, and will generally avoid any significant retraction of the ribs, other than the incidental deflection of the ribs which may occur when a cannula, trocar, or other means of tissue retraction is placed in an intercostal space. Such retraction of ribs will generally be avoided entirely, and if occurring at all, will be limited to deflection of less than about one centimeter. Preferably, all such intercostal ports will have a width (or diameter, if round) of less than 30 mm in order to fit within an intercostal space without significant rib retraction, and in many cases will have a width of less than 12 mm so as to minimize trauma.
In a first aspect, the invention provides a method of closed-chest repair of a heart valve. Utilizing the method of the invention, the patient""s heart is arrested and cardiopulmonary bypass is established. The interior of the patient""s chest cavity is viewed by means of a thoroacoscope or by directly looking through a cannula or other retracting means positioned in an intercostal space. A knife or scissors is introduced through an intercostal port into the patient""s chest, and the cutting means is used to first form an opening in the pericardium, then to form a cardiac penetration in a wall of the heart. One or more percutaneous cannulae, trocars, or other means of retracting tissue may be positioned in an incision or puncture within an intercostal space through which various instruments may be introduced into the chest cavity. These instruments may be positioned through the cardiac penetration to perform, for example, annuloplasty, quadrangular resection of valve leaflets, commissurotomy, reattachment of chordae tendonae or papillary muscle tissue, shortening of chordae tendonae, decalcification, and the like. Advantageously, all of these steps may be performed without cutting, removing, or substantially retracting the ribs or sternum, eliminating the pain, trauma, long recovery time, and complications associated with gross thoracotomy.
The patient""s heart is preferably arrested by occluding the patient""s aorta between the patient""s coronary ostia and the patient""s brachiocephalic artery with an expandable member on a distal end of an endovascular aortic catheter introduced through a peripheral artery such as a femoral artery. Cardioplegic fluid is then delivered through a lumen in the catheter into the patient""s aorta upstream of the expandable member to arrest cardiac function. Alternatively, or in addition to such antegrade cardioplegic fluid delivery, cardioplegic fluid may be delivered in a retrograde manner by means of a catheter positioned in the coronary sinus of the patient""s heart. In an alternative approach, an external cross-clamp may be placed thoracoscopically on the aorta through a small incision or cannula in the patient""s chest. Cardioplegic fluid may be delivered either through a cannula introduced thoracoscopically and inserted through the aortic wall, or through an endovascular aortic catheter extending from a peripheral artery into the ascending aorta upstream of the cross-clamp.
In a preferred embodiment of the method, a prosthetic annuloplasty ring is introduced through an intercostal port and into an internal chamber of the heart, and the ring is attached to the heart wall around the annulus of the valve within the internal chamber. Usually, the valve will first be sized by introducing a sizing device through the intercostal port and into the heart through the cardiac penetration, and positioning the sizing device adjacent to the valve to measure its size. A valve sizing disk attached to an elongated shaft or handle may be used for this purpose. Once the valve size has been determined, sutures are inserted in the native valve annulus and an annuloplasty ring of appropriate size is selected. The ring is attached to an elongated handle and the ring is introduced through an intercostal port and through the cardiac penetration into the heart. The annuloplasty ring is then secured to the annulus of the heart valve, by tying knots in the sutures extracorporeally and pushing the knots into the heart with an elongated knot-pusher. The sutures are preferably applied to the annuloplasty ring outside of the chest cavity, and the ring is slid along the sutures through the intercostal port and cardiac penetration up to the valve annulus. The sutures are then tied and trimmed using thoracoscopic instruments.
One advantage of the method of the invention is that it allows the surgeon to obtain access to the valve through an intercostal port and a cardiac penetration, assess the nature and extent of valve disease, and then decide whether to repair or replace the valve. If the disease is such that repair is inappropriate, the surgeon may elect to replace the valve with any of a variety of replacement valves. A valve replacement method according to the invention may include the step of removing all or part of the patient""s natural heart valve by means of a cutting tool introduced through an intercostal port and through the cardiac penetration into the heart. The method further comprises the step of introducing a replacement valve through an intercostal port and through the cardiac penetration into the internal chamber of the heart. The replacement valve is then fastened within the heart, usually by means of a suturing instrument introduced through an intercostal port and through the cardiac penetration. As with the annuloplasty method described above, sutures are usually applied to the valve outside of the chest, and the valve is slid along the sutures into the heart. The sutures are then tied and trimmed. The method may further include the step of sizing the patient""s heart valve before the replacement valve is introduced. In an exemplary embodiment, a sizing instrument is introduced through an intercostal port and through the cardiac penetration to measure the size of the valve annulus and to determine the size of the replacement valve.
In order to suture the annuloplasty ring or replacement valve to the interior of the heart, the sutures are preferably applied to the heart tissue, drawn out of the patient""s body through an intercostal port and then applied to the annuloplasty ring or replacement valve. The sutures may be radially arranged in spaced-apart locations about an organizer ring disposed outside of the patient""s body. The sutures are then held in tension as the annuloplasty ring or replacement valve is introduced into the interior of the heart and positioned in the natural valve position. The annuloplasty ring or replacement valve may be introduced by means of a specialized holder attached to an elongated handle, or simply pushed along the sutures into the chest cavity by means of the surgeon""s hands, then into the native valve position using conventional thoracoscopic instruments such as forceps or needle drivers.
In a particularly preferred embodiment, the heart valve comprises a mitral valve which is disposed between the left atrium and left ventricle of the patient""s heart. An intercostal port is created within an intercostal space in a right lateral portion of the patient""s chest, usually within the third, fourth, or fifth intercostal space. From this intercostal port, a cardiac penetration may be formed in the wall of the left atrium at a location which is generally aligned with the intercostal port. In this way, surgical instruments may be introduced from the intercostal port in the right chest to form the cardiac penetration, repair or excise the patient""s natural valve, and/or introduce and attach an annuloplasty ring or replacement valve.
In a further aspect of the invention, a system is provided for repairing a heart valve. The system includes an annuloplasty device and a device holder for releasably holding the annuloplasty device to facilitate introducing it through an intercostal port and into the heart. The device holder includes connection means for connecting the holder to an elongated handle. The connection means is configured to connect to the handle such that the handle, holder, and annuloplasty device together have a profile with a profile height smaller than the width of the intercostal space, usually less than about 30 mm and preferably less than about 25 mm. The annuloplasty device has a bottom side which is positioned in contact with the wall of the heart around the heart valve when the device is implanted. The bottom side defines a first plane which is generally perpendicular to a longitudinal (axial) axis of the annuloplasty device. In an exemplary configuration, the connection means connects to the handle such that the longitudinal axis of the handle forms an angle with the first plane selected so that handle may be used to introduce the annuloplasty ring through the intercostal port without contacting or retracting the ribs adjacent the intercostal port. The angle will usually be about 0xc2x0+/xe2x88x9245xc2x0, and preferably 0xc2x0+/xe2x88x9220xc2x0, but could also be outside of this range if the annuloplasty device is small relative to the size of the intercostal space.
The holder also includes a means for retaining the annuloplasty device on the holder, such as retention sutures, a retaining clip, or a pivoting leaf on the holder. The system may further include means for releasing the annuloplasty device from the holder, such as a cutting device for cutting the retention sutures which hold the annuloplasty device on the holder, or other device for releasing the mechanism which secures the annuloplasty device to the holder.
The annuloplasty device may be any of the commercially-available annuloplasty rings, may be either stiff or flexible, split or continuous, and may have any of a variety of shapes, including C-shaped, D-shaped, kidney-shaped, saddle-shaped racetrack-shaped, oval, semi-circular, and circular. The annuloplasty device may also be malleable or shapable into a desired shape, or may be flexible and resilient and secured in the heart in a shape which differs from its natural, unstressed shape.
The valve repair system may further include an elongated handle having a distal end mounted to the device holder and a proximal end opposite the distal end. The handle is configured to introduce the annuloplasty device into the patient""s heart through an intercostal port. Preferably, the handle is at least about 20 cm in length to allow positioning the annuloplasty device in the left atrium of the heart from a right lateral portion of the patient""s chest.
The handle may also include means for pivoting the annuloplasty device from a first orientation for introduction through the intercostal space to a second orientation for attachment in the patient""s heart. The pivoting means is configured for actuation from a proximal end of the handle. In this way, the annuloplasty device may be introduced edge-first through the intercostal space, then pivoted about an axis generally perpendicular to the handle into an orientation suitable for attachment within the patient""s heart, preferably wherein the first plane is perpendicular to the longitudinal axis of the handle.
While a variety of mechanisms may be utilized for connecting the holder to the handle, in an exemplary embodiment, the handle has a tongue pivotably coupled to its distal end, a movable actuator coupled to its proximal end, and a rod or cable extending through a lumen in the handle connecting the actuator to the tongue. The tongue is received in an aperture in the device holder, and includes a spring catch or other means for retaining the tongue in the aperture. The aperture has an open proximal end, a distal end opposite the proximal end, and an axis therebetween defining the direction in which the tongue is received in the aperture. The aperture is preferably oriented so that the axis forms an angle of 0xc2x0+/xe2x88x9245xc2x0 relative to the first plane of the annuloplasty device, facilitating introduction through an intercostal port. In this way, the tongue may be aligned with the longitudinal axis of the handle for edge-first introduction of the annuloplasty device through the intercostal port, then pivoted to an appropriate angle, usually about 90xc2x0, relative to the handle so that the first plane of the annuloplasty device is generally parallel to the interior wall of the heart to which it is to be attached.
As an alternative to pivoting the annuloplasty device, the annuloplasty device and device holder may be flexible, collapsible, or compressible so that it may be deformed or constrained into a shape which allows the device and holder to be introduced through an intercostal space into the thoracic cavity.
The system of the invention may also include a retraction means for retracting the chest wall tissue in a percutaneous penetration within an intercostal space, to facilitate introduction of instruments, visualization devices, valve sizers, annuloplasty devices, and replacement valves through the penetration without interference and without damaging tissue. The retraction means displaces the tissue around the percutaneous penetration to create a small opening, but does not significantly retract or deflect the ribs. The retraction means may comprise any of various types of tissue or wound retractors, but in a preferred embodiment comprises a cannula having a distal end positionable through the intercostal space and an inner lumen of sufficient size and shape to allow a replacement valve or annuloplasty device to be positioned through the cannula into the chest cavity. Preferably, the inner lumen has a width of between about 12 mm and about 30 mm, in order to allow the cannula to be positioned within the intercostal space with the ribs unretracted, while allowing the annuloplasty device or replacement valve to pass through the lumen with sufficient clearance. The inner lumen has a height of at least 25 mm, and usually at least 35 mm, to permit introduction of the annuloplasty device or replacement valve. Usually, the height is larger than the width, in a preferred embodiment, at least about 1.5 times the width. In this way, the annuloplasty device or replacement valve may be introduced in an edge-first manner through the lumen of the cannula, then pivoted 90xc2x0 into a face-first orientation for attachment within the heart.
Because the annuloplasty device or replacement valve may be attached within the heart with a plurality of individual sutures, the system may further include means for organizing sutures outside of the chest cavity. The suture organizing means preferably is attached to the proximal end of the access cannula described above, and comprises a plurality of slots arranged radially about the inner lumen of the cannula. In this way, as each suture is placed in the heart tissue, the free ends of the suture may be withdrawn through the lumen of the access cannula and placed in one of the slots. The free ends may then be placed through the sewing ring of the annuloplasty device or replacement valve, and the device or valve advanced through the inner lumen of the cannula and into the heart by sliding along the suture threads.
Preferably, the annuloplasty device is premounted to the device holder and the two are sterilized and packaged together in a sterile pack. In this way, the pack may be opened in the sterile operating room environment with the annuloplasty device and holder ready for immediate use. In some embodiments, the elongated delivery handle, sizing disks, access cannula or other retraction means, suture organizer, and/or other system components may be included in the sterile pack with the annuloplasty device and holder. Alternatively, the annuloplasty device could be packaged separately from the device holder and the device mounted to the holder in the operating room at the time of the valve repair procedure.
The delivery handle of the invention is configured not only for introducing the annuloplasty device through an intercostal port into the heart, but for introducing valve sizing devices and/or a replacement valve as well. In this way, the same handle may be used to first size the native valve, then to introduce an annuloplasty device to repair the mitral valve, or to introduce a replacement valve to replace the native valve.
Accordingly, the invention also provides a device for sizing a valve which includes both an elongated handle and a sizing disk attached to the distal end of the handle. The sizing disk is configured to connect to the handle in an orientation in which the handle and the sizing disk together have a profile with a profile height smaller than the width of the intercostal space through which the sizing disk is introduced, usually less than about 30 mm and preferably less than about 25 mm. In a preferred embodiment, the sizing disk is pivotably attached to the handle so that it may be introduced through the intercostal space in an edge-first orientation, and then pivoted into a face-first orientation for sizing the valve. The handle may halve, as described above, a tongue pivotably mounted to its distal end which is received in an aperture on the sizing disk. allowing the sizing disk to be oriented with its face generally parallel to the longitudinal axis of the handle for introduction, then perpendicular to the longitudinal axis for sizing the valve. For sizing a valve for an annuloplasty repair, the sizing disk usually has a shape corresponding generally to the natural shape of the native valve annulus, which is roughly oval, kidney-shaped or D-shaped. The sizing disk also includes notches or markings to measure the spacing between the trigones or commisures of the valve. For valve replacement procedures, the sizing disk is preferably round, corresponding to the shape of the replacement valve sewing ring.
The invention further provides a holder for a prosthesis for repairing or replacing a heart valve. The holder may be adapted for holding either an annuloplasty ring or a prosthetic heart valve. The holder includes a holder body having a top, a bottom, and a holder axis. A holding means is included on the holder body for releasably holding a prosthesis such that the central axis of the attachment ring of the prosthesis is approximately parallel to the holder axis. The holder further includes a connection means for connecting to an elongated handle for introducing the holder and prosthesis through an intercostal space. The connection means has a proximal end, a distal end, and a connection axis therebetween. The connection means is positioned on the holder body such that the connection axis is oriented at an angle relative to the holder axis selected so that, when the prosthesis is held by the holding means, the profile of the prosthesis and holder perpendicular to the connection axis has a height less than the width of the intercostal space, usually less than about 30 mm and preferably less than about 25 mm.
In a preferred embodiment, as described above, the handle has a pivotable tongue on its distal end, and the connection means comprises an aperture for receiving the tongue. The aperture has an open proximal end through which the tongue is received in a direction parallel to the connection axis. Alternatively, the connection means may comprise a threaded hole, snap fitting, luer fitting, threaded shaft, or tongue configured to connect to a complementary connector on the handle. Preferably, the connection means is removable from the handle to allow valve sizers, annuloplasty rings, and replacement valves to be interchanged on the same handle. However, the handle and holder may alternatively be permanently inseparably interconnected for dedicated use with a single annuloplasty device or replacement valve.
A further understanding of the nature and advantages of the invention may be realized by reference to the remaining portions of the specification and the drawings.